Slow scroll on UITableView images

Question

I'm displaying lots of images loaded directly from my app (not downloaded). My table view is slow when I scroll it the first time. It becomes smooth after all my cell has been displayed. I don't really know why.

I have an array of UIImage that I'm loading in the viewDidLoad. Then in my tableview delegate I just get the image at a given index path and set it to an UIImageView of my cell.

Do you know how I can improve performances ?

Vicky Vicky · Accepted Answer · 2014-06-30T07:59:39

just to share I have fixed and it worked very well Steps I followed.

1) Set the performSelectorInBAckground function with Cell as parameter passed that holds the scroll view or uiview to put many iamges.

2) In the background function load the image stored from application bundle or local file using imagewithContents of file.

3) Set the image to the imageView using this code.

    //// Start of optimisation - for iamges to load dynamically in cell with delay , make sure you call this function in performSelectorinBackground./////

    //Setting nil if any for safety
    imageViewItem.image = nil;

    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);

    dispatch_async(queue, ^{
        UIImage *image = // Load from file or Bundle as you want

        dispatch_sync(dispatch_get_main_queue(), ^{

            //Set the image to image view not, wither cell.imageview or [cell add subviw:imageview later ]
            [imageViewItem setImage:image];
            [imageViewItem setNeedsLayout];
        });
    });

    //// End of optimisation/////

This will load all images dynamically and also scroll the table view quite smoothly than previous slow and jerky behaviour.

All the best

Slow scroll on UITableView images

3 Answers